Bitmap 'patch' scaling.

When scaling a bitmap, currently we always scale the entire bitmap,
even if we only need a small section of the result.

This patch changes the code to take an optional 'clip' bbox, and
only scales as much of the input as as required for this output
region.

1 files changed, 27 insertions, 10 deletions

diff --git a/draw/draw_device.c b/draw/draw_device.c
index 9a238b73..1cb3e4b9 100644
--- a/draw/draw_device.c
+++ b/draw/draw_device.c
@@ -821,7 +821,7 @@ fz_draw_fill_shade(fz_device *devp, fz_shade *shade, fz_matrix ctm, float alpha)
 }
 
 static fz_pixmap *
-fz_transform_pixmap(fz_context *ctx, fz_pixmap *image, fz_matrix *ctm, int x, int y, int dx, int dy, int gridfit)
+fz_transform_pixmap(fz_context *ctx, fz_pixmap *image, fz_matrix *ctm, int x, int y, int dx, int dy, int gridfit, fz_bbox *clip)
 {
 	fz_pixmap *scaled;
 
@@ -831,7 +831,7 @@ fz_transform_pixmap(fz_context *ctx, fz_pixmap *image, fz_matrix *ctm, int x, in
 		fz_matrix m = *ctm;
 		if (gridfit)
 			fz_gridfit_matrix(&m);
-		scaled = fz_scale_pixmap(ctx, image, m.e, m.f, m.a, m.d);
+		scaled = fz_scale_pixmap(ctx, image, m.e, m.f, m.a, m.d, clip);
 		if (!scaled)
 			return NULL;
 		ctm->a = scaled->w;
@@ -845,9 +845,17 @@ fz_transform_pixmap(fz_context *ctx, fz_pixmap *image, fz_matrix *ctm, int x, in
 	{
 		/* Other orthogonal flip/rotation cases */
 		fz_matrix m = *ctm;
+		fz_bbox rclip;
 		if (gridfit)
 			fz_gridfit_matrix(&m);
-		scaled = fz_scale_pixmap(ctx, image, m.f, m.e, m.b, m.c);
+		if (clip)
+		{
+			rclip.x0 = clip->y0;
+			rclip.y0 = clip->x0;
+			rclip.x1 = clip->y1;
+			rclip.y1 = clip->x1;
+		}
+		scaled = fz_scale_pixmap(ctx, image, m.f, m.e, m.b, m.c, (clip ? &rclip : 0));
 		if (!scaled)
 			return NULL;
 		ctm->b = scaled->w;
@@ -860,7 +868,7 @@ fz_transform_pixmap(fz_context *ctx, fz_pixmap *image, fz_matrix *ctm, int x, in
 	/* Downscale, non rectilinear case */
 	if (dx > 0 && dy > 0)
 	{
-		scaled = fz_scale_pixmap(ctx, image, 0, 0, (float)dx, (float)dy);
+		scaled = fz_scale_pixmap(ctx, image, 0, 0, (float)dx, (float)dy, NULL);
 		return scaled;
 	}
 
@@ -878,6 +886,9 @@ fz_draw_fill_image(fz_device *devp, fz_pixmap *image, fz_matrix ctm, float alpha
 	fz_context *ctx = dev->ctx;
 	fz_draw_state *state = &dev->stack[dev->top];
 	fz_colorspace *model = state->dest->colorspace;
+	fz_bbox clip = fz_bound_pixmap(state->dest);
+
+	clip = fz_intersect_bbox(clip, state->scissor);
 
 	fz_var(scaled);
 
@@ -915,14 +926,14 @@ fz_draw_fill_image(fz_device *devp, fz_pixmap *image, fz_matrix ctm, float alpha
 		if (dx < image->w && dy < image->h)
 		{
 			int gridfit = alpha == 1.0f && !(dev->flags & FZ_DRAWDEV_FLAGS_TYPE3);
-			scaled = fz_transform_pixmap(ctx, image, &ctm, state->dest->x, state->dest->y, dx, dy, gridfit);
+			scaled = fz_transform_pixmap(ctx, image, &ctm, state->dest->x, state->dest->y, dx, dy, gridfit, &clip);
 			if (!scaled)
 			{
 				if (dx < 1)
 					dx = 1;
 				if (dy < 1)
 					dy = 1;
-				scaled = fz_scale_pixmap(ctx, image, image->x, image->y, dx, dy);
+				scaled = fz_scale_pixmap(ctx, image, image->x, image->y, dx, dy, NULL);
 			}
 			if (scaled)
 				image = scaled;
@@ -973,6 +984,9 @@ fz_draw_fill_image_mask(fz_device *devp, fz_pixmap *image, fz_matrix ctm,
 	int i;
 	fz_draw_state *state = &dev->stack[dev->top];
 	fz_colorspace *model = state->dest->colorspace;
+	fz_bbox clip = fz_bound_pixmap(state->dest);
+
+	clip = fz_intersect_bbox(clip, state->scissor);
 
 	if (image->w == 0 || image->h == 0)
 		return;
@@ -985,14 +999,14 @@ fz_draw_fill_image_mask(fz_device *devp, fz_pixmap *image, fz_matrix ctm,
 	if (dx < image->w && dy < image->h)
 	{
 		int gridfit = alpha == 1.0f && !(dev->flags & FZ_DRAWDEV_FLAGS_TYPE3);
-		scaled = fz_transform_pixmap(dev->ctx, image, &ctm, state->dest->x, state->dest->y, dx, dy, gridfit);
+		scaled = fz_transform_pixmap(dev->ctx, image, &ctm, state->dest->x, state->dest->y, dx, dy, gridfit, &clip);
 		if (!scaled)
 		{
 			if (dx < 1)
 				dx = 1;
 			if (dy < 1)
 				dy = 1;
-			scaled = fz_scale_pixmap(dev->ctx, image, image->x, image->y, dx, dy);
+			scaled = fz_scale_pixmap(dev->ctx, image, image->x, image->y, dx, dy, NULL);
 		}
 		if (scaled)
 			image = scaled;
@@ -1025,6 +1039,9 @@ fz_draw_clip_image_mask(fz_device *devp, fz_pixmap *image, fz_rect *rect, fz_mat
 	int dx, dy;
 	fz_draw_state *state = push_stack(dev);
 	fz_colorspace *model = state->dest->colorspace;
+	fz_bbox clip = fz_bound_pixmap(state->dest);
+
+	clip = fz_intersect_bbox(clip, state->scissor);
 
 	fz_var(mask);
 	fz_var(dest);
@@ -1066,14 +1083,14 @@ fz_draw_clip_image_mask(fz_device *devp, fz_pixmap *image, fz_rect *rect, fz_mat
 		if (dx < image->w && dy < image->h)
 		{
 			int gridfit = !(dev->flags & FZ_DRAWDEV_FLAGS_TYPE3);
-			scaled = fz_transform_pixmap(dev->ctx, image, &ctm, state->dest->x, state->dest->y, dx, dy, gridfit);
+			scaled = fz_transform_pixmap(dev->ctx, image, &ctm, state->dest->x, state->dest->y, dx, dy, gridfit, &clip);
 			if (!scaled)
 			{
 				if (dx < 1)
 					dx = 1;
 				if (dy < 1)
 					dy = 1;
-				scaled = fz_scale_pixmap(dev->ctx, image, image->x, image->y, dx, dy);
+				scaled = fz_scale_pixmap(dev->ctx, image, image->x, image->y, dx, dy, NULL);
 			}
 			if (scaled)
 				image = scaled;